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U.S. ZIP Codes Database 2026

Search by ZIP code, city, county, or state and find clear postal details with maps, time zones, and area code data.

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Frederick County ZIP Codes

Browse all ZIP Codes, cities, and associated area codes registered in Frederick County.

County State ZIP Code City Area Codes
Frederick County MD 21771 Mount Airy 227, 240, 301, 410, 443, 667
Frederick County MD 21773 Myersville 227, 240, 301
Frederick County MD 21774 New Market 227, 240, 301
Frederick County MD 21775 New Midway 240
Frederick County MD 21777 Point Of Rocks 227, 240, 301
Frederick County MD 21778 Rocky Ridge 227, 240, 301, 410, 443, 667
Frederick County MD 21780 Sabillasville 227, 240, 301
Frederick County MD 21788 Thurmont 227, 240, 301
Frederick County MD 21790 Tuscarora 227, 240, 301, 571, 703
Frederick County MD 21792 Unionville 240
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About U.S. ZIP Codes

ZIP codes are a United States Postal Service system introduced in 1963 to make mail routing more accurate and efficient. The standard format uses five digits, while ZIP+4 adds four more digits for a more precise delivery segment.

ZIP codes cover the United States, its territories, military mail routes, and other USPS delivery points. This directory organizes that data for practical lookup by ZIP code, city, county, and state.